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Self-propelled particles possessing permanent magnetic dipole moments occur naturally in magnetotactic bacteria and can be built into man-made systems such as active colloids or micro-robots. Yet, the interplay between self-propulsion and anisotropic dipole–dipole interactions on dynamic self-assembly in three dimensions (3D) remains poorly understood. We conduct Brownian dynamics simulations of active dipolar particles in 3D, focusing on the low-density regime, where dipolar hard spheres tend to form chain-like aggregates and percolated networks with increasing dipolar coupling strength. We find that strong active forces override dipolar attractions, effectively inhibiting chain-like aggregation and network formation. Conversely, activating particles with low to moderate forces results in a fluid composed of active chains and rings. At strong dipolar coupling strengths, this active fluid transitions into an active gel, consisting of a percolated network of active chains. Although the overall structure of the active gel remains interconnected, the network experiences more frequent configurational rearrangements due to the reduced bond lifetime of active dipolar particles. Consequently, particles exhibit enhanced translational and rotational diffusion within the active fluid of strings and active gels compared to their passive counterparts. We quantify the influence of activity on aggregate topology as they transition from branched structures to unconnected chains and rings. Our findings are summarized in a state diagram, delineating the impact of dipolar coupling strength and active force magnitude on the system. [ABSTRACT FROM AUTHOR]

Dermal fibroblasts play a crucial role in the formation of granulation tissue in skin wounds. Consequently, the differentiation, migration, and proliferation of dermal fibroblasts are considered key factors in the skin wound healing process. However, in patients with diabetic foot ulcers, the proliferation and migration of fibroblasts are impaired by reactive oxygen species and inflammatory factors impair. Therefore, a novel magnetic gelatin-hesperidin microrobots drug delivery system was developed using microfluidics. The morphology, motility characteristics, and drug release of the microrobot were assessed, along with its impact on the proliferation and migration of human dermal fibroblasts under high-glucose conditions. Subjected to a rotating magnetic field, the microrobots exhibit precise, controllable, and flexible autonomous motion, achieving a maximum speed of 9.237 µm/s. In vitro drug release experiments revealed that approximately 78% of the drug was released within 30 min. It was demonstrated through cellular experiments that the proliferation of human dermal fibroblasts was actively promoted by the nanorobot, the migration ability of fibroblasts in a high-glucose state was enhanced, and good biocompatibility was exhibited. Hence, our study may provide a novel drug delivery system with significant potential for promoting the healing of diabetic foot wounds. [ABSTRACT FROM AUTHOR]

Magnetic microrobots are controlled to exhibit a wide range of motions, allowing them to navigate complex environments and perform multifunctional tasks with high precision. This work presents a novel hybrid electromagnetic actuation system by integrating two distinct conventional configurations, such as a paired‐coils electromagnetic disc (EMD) system and a distributed electromagnetic array coil (EAC) system. In order to ensure the effective functioning of the microrobot, its motion dynamics are thoroughly analyzed to identify the critical kinetic parameters. For demonstration purposes, first, a mixing task is performed by employing a single microrobot actuated with simultaneous motions. The mixing efficiency is observed to reach 83% within 30 s, in contrast to the efficiency of control of 45%. Second, a structural reconfiguration function is demonstrated by employing an independent control of two U‐shaped microrobots to form a new I‐shaped microrobot. Last, differentiated motion control of multiple magnetic pads is demonstrated, resulting in various 2D static formations in the shapes of numbers and alphabets. The presented results hold great promise for advancing the field of microrobotics by offering a novel solution for versatile microrobot motion controls. [ABSTRACT FROM AUTHOR]

Maximizing materials utilization efficiency via enhancing their reconfigurability and multifunctionality offers a promising avenue in addressing the global challenges in sustainability. To this end, significant efforts have been made in developing reconfigurable multifunctional smart materials, which can exhibit remarkable behaviors such as morphing and self-healing. However, the difficulty in efficiently manipulating and controlling matter at the building block level with manageable cost and complexity, which is crucial to achieving superior responsiveness to environmental clues and stimuli, has significantly hindered the further development of such smart materials. Here we introduce a concept of Robo-Matter, which can be activated and controlled through external information exchange at the building block level, to enable a high-level of controllability, mutability and versatility for reconfigurable multifunctional smart materials. Using specially designed micro-robot building blocks with symmetry-breaking active motion modes, tunable anisotropic interactions, and interactive coupling with a programmable spatial-temporal dynamic light field, we demonstrate an emergent Robot-Matter duality, which enables a spectrum of desirable behaviors spanning from matter-like properties such as ultra-fast self-assembly and adaptivity, to robot-like properties including active force output, smart healing, smart morphing and infiltration. Our work demonstrates a promising direction for designing next-generation smart materials and large-scale robotic swarms. The authors introduce the concepts of Robo-Matter and Robot-Matter duality, using magnetic spinner micro-robots. A wide range of functionalities and applications beyond the capability of both traditional inert and active materials is enabled. [ABSTRACT FROM AUTHOR]

Small-scale robots with shape anisotropy have garnered significant scientific interest due to their enhanced mobility and precise control in recent years. Traditionally, these miniature robots are manufactured using established techniques such as molding, 3D printing, and microfabrication. However, the advent of microfluidics in recent years has emerged as a promising manufacturing technology, capitalizing on the precise and dynamic manipulation of fluids at the microscale to fabricate various complex-shaped anisotropic particles. This offers a versatile and controlled platform, enabling the efficient fabrication of small-scale robots with tailored morphologies and advanced functionalities from the microfluidic-derived anisotropic microparticles at high throughput. This review highlights the recent advances in the microfluidic fabrication of anisotropic microparticles and their potential applications in small-scale robots. In this review, the term 'small-scale robots' broadly encompasses micromotors endowed with capabilities for locomotion and manipulation. Firstly, the fundamental strategies for liquid template formation and the methodologies for generating anisotropic microparticles within the microfluidic system are briefly introduced. Subsequently, the functionality of shape-anisotropic particles in forming components for small-scale robots and actuation mechanisms are emphasized. Attention is then directed towards the diverse applications of these microparticle-derived microrobots in a variety of fields, including pollution remediation, cell microcarriers, drug delivery, and biofilm eradication. Finally, we discuss future directions for the fabrication and development of miniature robots from microfluidics, shedding light on the evolving landscape of this field. [ABSTRACT FROM AUTHOR]

There has been significant interest in the field of bio-inspired robotics, particularly in the development of flapping-wing robots from micro to bird size. Most flapping robots use lever-crank mechanisms or servomotors as wing flapping mechanisms. Servomotor-based flapping has the advantage of being able to generate various flapping patterns according to amplitude, offset, frequency, waveform, and other factors. However, it is not clear how these factors affect thrust generation. Therefore, this study focuses on the force generation and power consumption in different flapping patterns as well as the wing deformation during the flapping motion to provide some insights into the performance improvement. The results showed that the response characteristics of the actuators caused the thrust to saturate at high frequencies, and that sinusoidal pattern could generally achieve good performance and efficiency. [ABSTRACT FROM AUTHOR]

Despite the recent wide investigation on active cancer drug delivery, there are still strong medical unmet needs for active tumor‐environment responsive cancer drug delivery in terms of spatiotemporal control. Herein, a biohybrid system of pH‐responsive peptide nanotubes (PNTs)‐coated microalgae for active cancer drug delivery in response to the tumor‐environment is developed. The amphiphilic PNTs are effectively used to encapsulate cancer drugs and coat the living microalgae of C. reinhardtii by electrostatic interactions. The drug‐loaded PNTs‐based biohybrid microalgae maintain agile movement with phototaxis behavior. After in vitro characterization and cytotoxicity assessment, it is shown that the biohybrid microalgae could be phototactically localized to the cancer cells and pH‐responsively disassembled to release cancer drugs in a controlled manner. Finally, with the encapsulation of paclitaxel, the statistically significant suppression of tumor growth in xenograft tumor model animals is successfully demonstrated. Taken together, the feasibility of the multifunctional microrobotic platform for advanced cancer therapy is confirmed. [ABSTRACT FROM AUTHOR]

Dynamic and agile locomotion in legged robots enables them to overcome obstacles and navigate complex and unstructured terrain. However, the leg mechanisms and actuators needed for versatile locomotion are much more challenging to manufacture and integrate in sub‐gram scale robots. Herein, Picotaur, a 15.4 mg hexapedal robot with legs that enable various locomotion tasks such as turning, climbing 3D‐printed stairs, and pushing loads for the first time at these size scales, is presented. 3D printing with two‐photon polymerization enables the manufacture of electrostatically driven 2 degrees of freedom legs on a robot body made from a flexible printed circuit board. Based on simple control inputs, Picotaur can achieve alternating tripod gaits, reaching speeds up to 57 mm (7.2 body lengths) per second, as well as pronking gaits to tackle a wider variety of terrain. This approach to manufacturing and controlling legged robots at smaller scales provides a path forward toward robots that can be used for practical applications ranging from inspection to exploration and rival the performance of insects at similar size scales. [ABSTRACT FROM AUTHOR]

Micro/nanorobots with active movement capabilities provide a new option for the treatment of glioblastoma (GBM). However, the long working distance of intravenous injection and the protection of the blood‐brain barrier can prevent micro/nanorobots from reaching the target location. Photodynamic therapy (PDT) has gradually appeared in GBM treatment research. The limitation of the penetrating strength of the light source will nevertheless hinder the application range of PDT. Herein, a magnetic continuum robot (MCR) to deliver optical fibers and microrobots for combined chemotherapy and PDT of GBM is used. The prepared magnetic diatom microrobots can effectively move in biological fluids and move upstream. Vacuum loading can improve the drug loading efficiency. The photosensitizer in the frustule cavity can be explosively released in a short time through ultrasound. The chemotherapeutic drugs have long‐term and pH‐sensitivity release characteristics. In vitro cell experiments showed that the combined administration of TMZ‐loaded microrobots and photosensitizer‐loaded microrobots has a synergistic effect. The in vitro model demonstrated that an MCR can deliver an optical fiber and drug‐loaded microrobots. This enables cross‐scale delivery of microrobots and deep PDT. This delivery method may expand the drug selectivity for GBM treatment and provide a new possibility for intracranial PDT. [ABSTRACT FROM AUTHOR]

Synchronization plays an important role in propelling microrobots, especially for those driven by an external magnetic field. Here, we substantially contribute to the understanding of a novel out-of-sync phenomenon called "slip-out", which has been recently discovered in experiments of an artificial microtubule (AMT). In a deterministic situation, we interpret and quantitatively characterize the switching in such a system between the stick and slip modes, whose different combinations over time define four long-term states. The stick-and-slip state is the most typical "slip-out" state with periodic switching, caused by both the phase lock between the microrod and the magnetic field, and the time-dependent magnetic moment. We then illustrate that thermal noise leads to stochastic switching by stimulating the phase difference across a specific threshold randomly. Finally, we reproduce the average velocity simulatively, which is highly consistent with real experiments. Importantly, the nearly permanent slip state is probed by our analysis of long-term states rather than observing real experiments. The investigation supports the design and operational strategies of AMT and other microrobots driven by magnetic fields. [ABSTRACT FROM AUTHOR]

Oral administration is the most simple, noninvasive, convenient treatment. With the increasing demands on the targeted drug delivery, the traditional oral treatment now is facing some challenges: 1) biologics how to implement the oral treatment and ensure the bioavailability is not lower than the subcutaneous injections; 2) How to achieve targeted therapy of some drugs in the gastrointestinal tract? Based on these two issues, drug delivery microrobots have shown great application prospect in oral drug delivery due to their characteristics of flexible locomotion or driven ability. Therefore, this paper summarizes various drug delivery microrobots developed in recent years and divides them into four categories according to different driving modes: magnetic-controlled drug delivery microrobots, anchored drug delivery microrobots, self-propelled drug delivery microrobots and biohybrid drug delivery microrobots. As oral drug delivery microrobots involve disciplines such as materials science, mechanical engineering, medicine, and control systems, this paper begins by introducing the gastrointestinal barriers that oral drug delivery must overcome. Subsequently, it provides an overview of typical materials involved in the design process of oral drug delivery microrobots. To enhance readers' understanding of the working principles and design process of oral drug delivery microrobots, we present a guideline for designing such microrobots. Furthermore, the current development status of various types of oral drug delivery microrobots is reviewed, summarizing their respective advantages and limitations. Finally, considering the significant concerns regarding safety and clinical translation, we discuss the challenges and prospections of clinical translation for various oral drug delivery microrobots presented in this paper, providing corresponding suggestions for addressing some existing challenges.

The pervasive presence of micro/nanoplastics in the environment is a significant threat to ecosystems and human health, demanding effective remediation strategies. Traditional methods for extracting these pollutants from water are often inadequate, typically leaving environmentally harmful residues. In response, this work introduces an innovative approach using reconfigurable and regenerable liquid metal microrobots (LiquidBots) that are magnetically driven to actively sequester micro/nanoplastics from aquatic environments. These LiquidBots utilize a coating of gallium oxide for enhanced adhesion and electrostatic interaction to capture over 80% of nanoplastics present in the solution. Additionally, the LiquidBots can be easily regenerated through sonication, which dislodges captured nanoplastics, allowing the microrobots to be reused. This novel technology offers a highly efficient, adaptable, and sustainable solution to combat the micro/nanoplastic pollution crisis. [ABSTRACT FROM AUTHOR]

Catalysis is a foundational pillar of modern synthetic chemistry, essential for countless industrial processes. Traditional catalysts are often static, either immobilized or dispersed in fluid media. The innovative concept of catalytic microrobots allows the introduction of self‐propelled and navigable catalyst particles that are engineered for dynamic and customizable catalysis. Catalytic microrobots are microscale devices with the inherent ability to move and swarm, designed to execute complex tasks in diverse environments, including biomedicine, and environmental remediation. Typically confined to aqueous media, their use in synthetic chemical reactions remains largely unexplored. Here, microrobots are presented as adaptable self‐propelled, self‐mixing micro‐catalysts for the Baeyer–Villiger oxidation, a key industrial process. Zeolite microstructures are tailored, outfitted with magnetic nanoparticles to create zeolite‐based microrobots (ZeoBOTs) that are maneuverable in magnetic fields. Uniquely, these ZeoBOTs are not limited to water but can operate in organic solvents, facilitating the Baeyer–Villiger oxidation in non‐aqueous conditions. Comparative analysis with static ZeoBOTs reveals that the dynamic, “on‐the‐fly” movement of the microrobots significantly enhances reaction yields. The findings herald a new era for synthetic chemistry, demonstrating the potential of microrobots as versatile catalysts beyond aqueous systems, and setting the stage for their broader application in synthetic processes. [ABSTRACT FROM AUTHOR]

The micro crawling robot exhibits significant potential applications in various fields such as fault detection, disaster relief, and environmental monitoring. This article introduces a high‐performance millimeter scale crawling robot driven by a miniature electromagnetic linear actuator (MELA) with a body length of 5–6 mm and a mass of 80 mg. In this article, the working principle of the micro robot is analyzed and validated, and the influence of current, frequency, and angle α between the direction of actuator's force and the crawling surface on the crawling speed are analyzed through experiments. Results show that the optimal α ranges from 50° to 55°, and a specific current and frequency are identified to achieve maximum crawling speed for robot with particular α. When α is 50°, with a current of 300 mA and a frequency of 200 Hz, the robot reached the maximum speed of 20.2 Body Length s−1(BL s−1). The proposed robot can crawl at 12 BL s−1 with a load of 110 mg, and support a maximum load of 400 mg. Additionally, the robot demonstrated diverse capabilities such as climbing on a 10° slope with a load of 110 mg, jumping on a 1 mm obstacle, and crawling on surfaces of various materials. [ABSTRACT FROM AUTHOR]

Highlights: A systematic review of recent advances of microrobots applied in the musculoskeletal system with an emphasis on design strategies of microrobotic systems for tissue regeneration. The fabrication, motion and control, and image-guided delivery of microrobots in the musculoskeletal system are reviewed based on the up-to-date works. Prospects and challenges for future clinical translation of microrobots in the musculoskeletal system and regenerative medicine are discussed. Disorders of the musculoskeletal system are the major contributors to the global burden of disease and current treatments show limited efficacy. Patients often suffer chronic pain and might eventually have to undergo end-stage surgery. Therefore, future treatments should focus on early detection and intervention of regional lesions. Microrobots have been gradually used in organisms due to their advantages of intelligent, precise and minimally invasive targeted delivery. Through the combination of control and imaging systems, microrobots with good biosafety can be delivered to the desired area for treatment. In the musculoskeletal system, microrobots are mainly utilized to transport stem cells/drugs or to remove hazardous substances from the body. Compared to traditional biomaterial and tissue engineering strategies, active motion improves the efficiency and penetration of local targeting of cells/drugs. This review discusses the frontier applications of microrobotic systems in different tissues of the musculoskeletal system. We summarize the challenges and barriers that hinder clinical translation by evaluating the characteristics of different microrobots and finally point out the future direction of microrobots in the musculoskeletal system. [ABSTRACT FROM AUTHOR]

As micron-sized objects, mobile microrobots have shown significant potential for future biomedical applications, such as targeted drug delivery and minimally invasive surgery. However, to make these microrobots viable for clinical applications, several crucial aspects should be implemented, including customizability, motion-controllability, imageability, biodegradability, and biocompatibility. Developing materials to meet these requirements is of utmost importance. Here, a gelatin methacryloyl (GelMA) and (2-(4-vinylphenyl)ethene-1,1,2-triyl)tribenzene (TPEMA)-based multifunctional hydrogel with 3D printability, fluorescence imageability, biodegradability, and biocompatibility is demonstrated. By using 3D direct laser writing method, the hydrogel exhibits its versatility in the customization and fabrication of 3D microstructures. Spherical hydrogel microrobots were fabricated and decorated with magnetic nanoparticles on their surface to render them magnetically responsive, and have demonstrated excellent movement performance and motion controllability. The hydrogel microstructures also represented excellent drug loading/release capacity and degradability by using collagenase, along with stable fluorescence properties. Moreover, cytotoxicity assays showed that the hydrogel was non-toxic, as well as able to support cell attachment and growth, indicating excellent biocompatibility of the hydrogel. The developed multifunctional hydrogel exhibits great potential for biomedical microrobots that are integrated with customizability, 3D printability, motion controllability, drug delivery capacity, fluorescence imageability, degradability, and biocompatibility, thus being able to realize the real in vivo biomedical applications of microrobots. [ABSTRACT FROM AUTHOR]

This study investigates the dynamic fluctuations of pH caused by gastric acid secretion, a process of both biological and clinical significance, with microrobots. Abnormal patterns of acidity often indicate gastrointestinal diseases, underlying the importance of precise intragastric pH monitoring. Traditional methods using fluorescent probes face challenges due to their faint solid‐state fluorescence, limited target specificity, and accuracy. To overcome these obstacles, pH‐responsive fluorescent organic microparticles decorated with magnetite (Fe3O4) nanoparticles are engineered. These microrobots exhibit a unique fluorescence switching capability at a critical pH, enabling the monitoring of gastric acidity. The magnetic part of these microrobots ensures magnetic maneuverability to enable targeted navigation. The microrobots' fluorescence switching mechanism is elucidated through comprehensive spectroscopy, microscopy, and X‐ray diffraction analyses, revealing molecular‐level structural transformations upon interaction with gastric acid and antacids. These transformations, specifically protonation and deprotonation of the microrobots' fluorescent components, prompt a distinct fluorescence response correlating with pH shifts. In vitro and ex vivo experiments, simulating stomach conditions, confirm the microrobots' efficacy in pH‐responsive imaging. The results showcase the promising diagnostic potential of microrobots for gastrointestinal tract diseases, marking a significant advancement in imaging‐based medical diagnostics at targeted locations. [ABSTRACT FROM AUTHOR]

The urgent demand for addressing dye contaminants in water necessitates the development of microrobots that exhibit remote navigation, rapid removal, and molecular identification capabilities. The progress of microrobot development is currently hindered by the scarcity of multifunctional materials. In this study, a plasmonic MXene hydrogel (PM‐Gel) is synthesized by combining bimetallic nanocubes and Ti3C2Tx MXene through the rapid gelation of degradable alginate. The hydrogel can efficiently adsorb over 60% of dye contaminants within 2 min, ultimately achieving a removal rate of >90%. Meanwhile, the hydrogel exhibits excellent sensitivity in surface enhanced Raman scattering (SERS) detection, with a limit of detection (LOD) as low as 3.76 am. The properties of the plasmonic hydrogel can be further adjusted for various applications. As a proof‐of‐concept experiment, thermosensitive polymers and superparamagnetic particles are successfully integrated into this hydrogel to construct a versatile, light‐responsive microrobot for dye contaminants. With magnetic and optical actuation, the robot can remotely sample, identify, and remove pollutants in maze‐like channels. Moreover, light‐driven hydrophilic‐hydrophobic switch of the microrobots through photothermal effect can further enhance the adsorption capacity and reduced the dye residue by up to 58%. These findings indicate of a broad application potential in complex real‐world environments. [ABSTRACT FROM AUTHOR]

Light‐driven micro/nanorobots (LMNRs) are tiny, untethered machines with great potential in fields like precision medicine, nano manufacturing, and various other domains. However, their practicality hinges on developing light‐manipulation strategies that combine versatile functionalities, flexible design options, and precise controllability. Our study introduces an innovative approach to construct micro/nanorobots (MNRs) by utilizing micro/nanomotors as fundamental building blocks. Inspired by silicon Metal‐Insulator‐Semiconductor (MIS) solar cell principles, we design a new type of optomagnetic hybrid micromotors (OHMs). These OHMs have been skillfully optimized with integrated magnetic constituent, resulting in efficient light propulsion, precise magnetic navigation, and the potential for controlled assembly. One of the key features of the OHMs is their ability to exhibit diverse motion modes influenced by fracture surfaces and interactions with the environment, streamlining cargo conveyance along "micro expressway"—the predesigned microchannels. Further enhancing their versatility, a template‐guided assembly strategy facilitates the assembly of these micromotors into functional microrobots, encompassing various configurations such as "V‐shaped", "N‐shaped", and 3D structured microrobots. The heightened capabilities of these microrobots, underscore the innovative potential inherent in hybrid micromotor design and assembly, which provides a foundational platform for the realization of multi‐component microrobots. Our work moves a step toward forthcoming microrobotic entities boasting advanced functionalities. [ABSTRACT FROM AUTHOR]

Magnetic microrobots and nanoparticles offer unique capabilities for medical applications by granting unprecedented access to intricate and delicate anatomical structures. Nevertheless, an intuitive manipulation approach remains a challenge due to their small size and limited feedback. This study presents a new method for magnetic microrobot and nanoparticle control that employs virtual reality (VR), creating an immersive and realistic view of the bodily anatomy and the microrobot within. This study compares three manipulation modes: a traditional mode using 2D displays, VR mode using a VR headset and touch controllers, and VR autonomous programmed maneuvering. It is shown that VR‐assisted modes reduce the manipulation time by improving spatial awareness. Nanoparticles in a VR environment are also manipulated. The proposed method will find applications in terms of intuitive, immersive microrobots or magnetic nanoparticle control in complex biological environments, thus in many medical procedures and for drug and cell delivery. The immersive nature of this approach enhances the ability of the user to perceive and understand complex anatomical structures, facilitating better navigation within delicate environments; both dexterity and spatial awareness are improved. Thus, it is shown how microrobots and magnetic nanoparticles can be controlled using immersive simulations to improve both visualization and manipulation. [ABSTRACT FROM AUTHOR]

Energy serves as the foundational element for all active functions within microrobots. Harvesting devices, such as photovoltaic cells and coils, play a crucial role in converting diverse forms of energy into electricity, while energy storage devices enable uninterrupted operation and liberate microrobots from dependence on external sources. Despite the evident importance of energy, there exists a significant disconnect between the development of energy devices and their integration into microrobotic systems, hampering the deployment of microrobots across diverse fields from agriculture to microsurgery. Here, for transcending the "material for material's sake" focus on simple generic metrics for material optimization, such as energy density, advocating attention to the higher tier transformation of material metrics that determine device‐level performance and so make a meaningful contribution to microrobotic technology is argued. Appropriate metrics for microrobotic swarms challenge the stereotype that tiny energy supplies are impractical; instead, swarms simplify individual microrobotic functions, reducing single energy supply requirements and utilizing swarm energy distribution and management. In addition to essential evaluations of the environmental and social impacts of intelligent microrobotic swarms for their safe and beneficial implementation, research targeting these higher‐tier metrics is crucial to connecting energy material research and microrobot developments effectively. [ABSTRACT FROM AUTHOR]

Cytokines have been identified as key contributors to the development of inflammatory bowel disease (IBD), yet conventional treatments often prove inadequate and carry substantial side effects. Here, we present an innovative biohybrid robotic system, termed "algae-MΦNP-robot," for addressing IBD by actively neutralizing colonic cytokine levels. Our approach combines moving green microalgae with macrophage membrane–coated nanoparticles (MΦNPs) to efficiently capture proinflammatory cytokines "on the fly." The dynamic algae-MΦNP-robots outperformed static counterparts by enhancing cytokine removal through continuous movement, better distribution, and extended retention in the colon. This system is encapsulated in an oral capsule, which shields it from gastric acidity and ensures functionality upon reaching the targeted disease site. The resulting algae-MΦNP-robot capsule effectively regulated cytokine levels, facilitating the healing of damaged epithelial barriers. It showed markedly improved prevention and treatment efficacy in a mouse model of IBD and demonstrated an excellent biosafety profile. Overall, our biohybrid algae-MΦNP-robot system offers a promising and efficient solution for IBD, addressing cytokine-related inflammation effectively. Editor's summary: Regulating cytokine activity can effectively manage inflammatory bowel disease, but traditional treatments are immunosuppressant or only target specific cytokines. By combining the robust motion of green algae with the binding abilities of macrophage membrane–coated nanoparticles, Li et al. developed a biohybrid microrobot that captured and removed a range of proinflammatory cytokines in vitro. The algae-based robots were encapsulated for protective passage through the stomach and administered to mice. In vivo studies confirmed biosafety and successful prevention and treatment of inflammatory bowel disease in a mouse model. The algae-based robots also hold potential for treatment of other cytokine-related disorders. —Melisa Yashinski [ABSTRACT FROM AUTHOR]

Lung metastasis poses a formidable challenge in the realm of cancer treatment, with conventional chemotherapy often falling short due to limited targeting and low accumulation in the lungs. Here, we show a microrobot approach using motile algae for localized delivery of drug-loaded nanoparticles to address lung metastasis challenges. The biohybrid microrobot [denoted "algae-NP(DOX)-robot"] combines green microalgae with red blood cell membrane-coated nanoparticles containing doxorubicin, a representative chemotherapeutic drug. Microalgae provide autonomous propulsion in the lungs, leveraging controlled drug release and enhanced drug dispersion to exert antimetastatic effects. Upon intratracheal administration, algae-NP(DOX)-robots efficiently transport their drug payload deep into the lungs while maintaining continuous motility. This strategy leads to rapid drug distribution, improved tissue accumulation, and prolonged retention compared to passive drug-loaded nanoparticles and free drug controls. In a melanoma lung metastasis model, algae-NP(DOX)-robots exhibit substantial improvement in therapeutic efficacy, reducing metastatic burden and extending survival compared to control groups. [ABSTRACT FROM AUTHOR]

The field of synthetic active matter has, thus far, been led by efforts to create point-like, isolated (yet interacting) self-propelled objects (e.g. colloids, droplets, microrobots) and understanding their collective dynamics. The design of flexible, freely jointed active assemblies from autonomously powered sub-components remains a challenge. Here, we report freely-jointed active polymers created using self-propelled droplets as monomeric units. Our experiments reveal that the self-shaping chemo-hydrodynamic interactions between the monomeric droplets give rise to an emergent rigidity (the acquisition of a stereotypical asymmetric C-shape) and associated ballistic propulsion of the active polymers. The rigidity and propulsion of the chains vary systematically with their lengths. Using simulations of a minimal model, we establish that the emergent polymer dynamics are a generic consequence of quasi two-dimensional confinement and auto-repulsive trail-mediated chemical interactions between the freely jointed active droplets. Finally, we tune the interplay between the chemical and hydrodynamic fields to experimentally demonstrate oscillatory dynamics of the rigid polymer propulsion. Altogether, our work highlights the possible first steps towards synthetic self-morphic active matter. While synthetic active matter research has concentrated on developing point-like, interacting entities, designing freely jointed active assemblies from autonomously powered components has remained a challenge. Here, the authors introduce freely jointed active polymers created from self-propelled droplets, uncovering emergent rigidity and propulsion, thereby advancing towards self-morphic synthetic materials. [ABSTRACT FROM AUTHOR]

Recent years have witnessed a surge in the application of microrobots within the medical sector, with hydrogel microrobots standing out due to their distinctive advantages. These microrobots, characterized by their exceptional biocompatibility, adjustable physico-mechanical attributes, and acute sensitivity to biological environments, have emerged as pivotal tools in advancing medical applications such as targeted drug delivery, wound healing enhancement, bio-imaging, and precise surgical interventions. The capability of hydrogel microrobots to navigate and perform tasks within complex biological systems significantly enhances the precision, efficiency, and safety of therapeutic procedures. Firstly, this paper delves into the material classification and properties of hydrogel microrobots and compares the advantages of different hydrogel materials. Furthermore, it offers a comprehensive review of the principal categories and recent innovations in the synthesis, actuation mechanisms, and biomedical application of hydrogel-based microrobots. Finally, the manuscript identifies prevailing obstacles and future directions in hydrogel microrobot research, aiming to furnish insights that could propel advancements in this field. [ABSTRACT FROM AUTHOR]

Recent technological advances have made it possible to produce tiny robots equipped with simple sensors and effectors. Micro-robots are particularly suitable for scenarios such as exploration of hostile environments, and emergency intervention, e.g., in areas subject to earthquakes or fires. A crucial desirable feature of such a robot is the capability of adapting to the specific environment in which it has to operate. Given the limited computational capabilities of a micro-robot, this property cannot be achieved by complicated software but it rather should come from the flexibility of simple control mechanisms, such as the sensory–motor loop. In this work, we explore the possibility of equipping simple robots controlled by Boolean networks with the capability of modulating their sensory–motor loop such that their behavior adapts to the incumbent environmental conditions. This study builds upon the cybernetic concept of homeostasis, which is the property of maintaining essential parameters inside vital ranges, and analyzes the performance of adaptive mechanisms intervening in the sensory–motor loop. In particular, we focus on the possibility of maneuvering the robot's effectors such that both their connections to network nodes and environmental features can be adapted. As the actions the robot takes have a feedback effect to its sensors mediated by the environment, this mechanism makes it possible to tune the sensory–motor loop, which, in turn, determines the robot's behavior. We study this general setting in simulation and assess to what extent this mechanism can sustain the homeostasis of the robot. Our results show that controllers made of random Boolean networks in critical and chaotic regimes can be tuned such that their homeostasis in different environments is kept. This outcome is a step towards the design and deployment of controllers for micro-robots able to adapt to different environments. [ABSTRACT FROM AUTHOR]

Multimodal motion capability is an emerging topic in the robotics field, and this paper presents a hybrid robot system maneuvering in both terrestrial and aerial environments. Firstly, a micro quadruped–quadrotor robot with onboard sensing and computing is developed. This robot incorporates both the high mobility of unmanned aerial vehicles and the long endurance of mobile robots on the ground. A coordinated motion control scheme is then exploited for adaptive terrestrial–aerial motion transition. In this scheme, a bio-inspired terrestrial locomotion controller is proposed to generate various quadruped locomotions, and a model-based aerial locomotion controller is proposed to generate various quadrotor configurations. Then, an unified motion controller for the two subsystems which dynamically adjusts crawling and flying motion in a complicated environment is presented. Consequently, several practical trials are conducted to demonstrate the adaptability and the robustness of the proposed system. [ABSTRACT FROM AUTHOR]

In recent years, the field of microrobots has exploded, yielding many exciting new functions and applications, from object grasping and release to in vivo drug transport. Smart responsive materials have had a profound impact on the field of microrobots and have given them unique functions and structures. We analyze three aspects of microrobots, in which the future development of microrobots requires more efforts to be invested, and in which smart materials play a significant role in the development of microrobots. These three aspects are smart materials for building microrobots, manufacturing methods, and the functions and applications they achieve. In this review, we discuss the deformation mechanism of materials in response to external stimuli, starting from smart materials, and discuss fabrication methods to realize microrobots, laying the theoretical foundation for future smart material-based microrobots to realize their intelligence and programmability. [ABSTRACT FROM AUTHOR]

As one of the most significant research topics in robotics, microrobots hold great promise in biomedicine for applications such as targeted diagnosis, targeted drug delivery, and minimally invasive treatment. This paper proposes an enhanced YOLOv5 (You Only Look Once version 5) microrobot detection and tracking system (MDTS), incorporating a visual tracking algorithm to elevate the precision of small-target detection and tracking. The improved YOLOv5 network structure is used to take magnetic bodies with sizes of 3 mm and 1 mm and a magnetic microrobot with a length of 2 mm as the pretraining targets, and the training weight model is used to obtain the position information and motion information of the microrobot in real time. The experimental results show that the accuracy of the improved network model for magnetic bodies with a size of 3 mm is 95.81%, representing an increase of 2.1%; for magnetic bodies with a size of 1 mm, the accuracy is 91.03%, representing an increase of 1.33%; and for microrobots with a length of 2 mm, the accuracy is 91.7%, representing an increase of 1.5%. The combination of the improved YOLOv5 network model and the vision algorithm can effectively realize the real-time detection and tracking of magnetically controlled microrobots. Finally, 2D and 3D detection and tracking experiments relating to microrobots are designed to verify the robustness and effectiveness of the system, which provides strong support for the operation and control of microrobots in an in vivo environment. [ABSTRACT FROM AUTHOR]

Magnetic soft microrobots have a wide range of applications in targeted drug therapy, cell manipulation, and other aspects. Currently, the research on magnetic soft microrobots is still in the exploratory stage, and most of the research focuses on a single helical structure, which has limited space to perform drug-carrying tasks efficiently and cannot satisfy specific medical goals in terms of propulsion speed. Therefore, balancing the motion speed and drug-carrying performance is a current challenge to overcome. In this paper, a magnetically controlled cone-helix soft microrobot structure with a drug-carrying function is proposed, its helical propulsion mechanism is deduced, a dynamical model is constructed, and the microrobot structure is prepared using femtosecond laser two-photon polymerization three-dimensional printing technology for magnetic drive control experiments. The results show that under the premise of ensuring sufficient drug-carrying space, the microrobot structure proposed in this paper can realize helical propulsion quickly and stably, and the speed of motion increases with increases in the frequency of the rotating magnetic field. The microrobot with a larger cavity diameter and a larger helical pitch exhibits faster rotary advancement speed, while the microrobot with a smaller helical height and a smaller helical cone angle outperforms other structures with the same feature sizes. The microrobot with a cone angle of 0.2 rad, a helical pitch of 100 µm, a helical height of 220 µm, and a cavity diameter of 80 µm achieves a maximum longitudinal motion speed of 390 µm/s. [ABSTRACT FROM AUTHOR]

Dynamic and agile locomotion in legged robots enables them to overcome obstacles and navigate complex and unstructured terrain. However, the leg mechanisms and actuators needed for versatile locomotion are much more challenging to manufacture and integrate in sub‐gram scale robots. Herein, Picotaur, a 15.4 mg hexapedal robot with legs that enable various locomotion tasks such as turning, climbing 3D‐printed stairs, and pushing loads for the first time at these size scales, is presented. 3D printing with two‐photon polymerization enables the manufacture of electrostatically driven 2 degrees of freedom legs on a robot body made from a flexible printed circuit board. Based on simple control inputs, Picotaur can achieve alternating tripod gaits, reaching speeds up to 57 mm (7.2 body lengths) per second, as well as pronking gaits to tackle a wider variety of terrain. This approach to manufacturing and controlling legged robots at smaller scales provides a path forward toward robots that can be used for practical applications ranging from inspection to exploration and rival the performance of insects at similar size scales.

Despite the recent wide investigation on active cancer drug delivery, there are still strong medical unmet needs for active tumor‐environment responsive cancer drug delivery in terms of spatiotemporal control. Herein, a biohybrid system of pH‐responsive peptide nanotubes (PNTs)‐coated microalgae for active cancer drug delivery in response to the tumor‐environment is developed. The amphiphilic PNTs are effectively used to encapsulate cancer drugs and coat the living microalgae of C. reinhardtii by electrostatic interactions. The drug‐loaded PNTs‐based biohybrid microalgae maintain agile movement with phototaxis behavior. After in vitro characterization and cytotoxicity assessment, it is shown that the biohybrid microalgae could be phototactically localized to the cancer cells and pH‐responsively disassembled to release cancer drugs in a controlled manner. Finally, with the encapsulation of paclitaxel, the statistically significant suppression of tumor growth in xenograft tumor model animals is successfully demonstrated. Taken together, the feasibility of the multifunctional microrobotic platform for advanced cancer therapy is confirmed.

Microgripper is a small‐miniaturized robotic device employed to maneuver sub‐millimeter‐sized particles or objects that are too small to be manipulated by human hands or conventional tools. The design and fabrication of the microgripper pose challenges due to the integration of actuation components into their structure. To address this challenge, the authors in this work presented a novel magnetic microgripper wherein the functions of the actuation components are executed by the two pairs of microgripper arms made up of magnetic material. A custom‐made electromagnetic system consisting of eight coils is employed to externally control these arms, enabling precise execution of gripping up to a maximum of two microparticles per working cycle. By varying the magnetic field strength from 20 to 120 mT, a wide range of gripper‐arms opening distance is achieved, spanning from 0.3 to 1.3 mm. Consequently, the microgripper is demonstrated to grip different sizes of microparticles ranging from 0.3 to 1.2 mm. As part of the motion control capabilities, the microgripper is demonstrated to orient and navigate across a 360‐degree range within the microfluidic environment. The presented microgripper holds promise for manipulating a wide variety of microparticle sizes and shapes, offering potential for high‐throughput applications [ABSTRACT FROM AUTHOR]

Lactic acid (LA) accumulation in the tumor microenvironment poses notable challenges to effective tumor immunotherapy. Here, an intelligent tumor treatment microrobot based on the unique physiological structure and metabolic characteristics of Veillonella atypica (VA) is proposed by loading Staphylococcus aureus cell membrane-coating BaTiO3 nanocubes (SAM@BTO) on the surface of VA cells (VA-SAM@ BTO) via click chemical reaction. Following oral administration, VA-SAM@ BTO accurately targeted orthotopic colorectal cancer through inflammatory targeting of SAM and hypoxic targeting of VA. Under in vitro ultrasonic stimulation, BTO catalyzed two reduction reactions (O2 → •O2- and CO2 → CO) and three oxidation reactions (H2O → •OH, GSH → GSSG, and LA → PA) simultaneously, effectively inducing immunogenic death of tumor cells. BTO catalyzed the oxidative coupling of VA cells metabolized LA, effectively disrupting the immunosuppressive microenvironment, improving dendritic cell maturation and macrophage M1 polarization, and increasing effector T cell proportions while decreasing regulatory T cell numbers, which facilitates synergetic catalysis and immunotherapy. [ABSTRACT FROM AUTHOR]

Bio‐inspired micro soft robots mimic biologically specific body structures and movement mechanisms by utilizing bionic principles. Because of its soft body, it can adapt to complex external environments. However, the existing polymer material system is single and the fabrication process is limited. How to further reduce soft robot size has become a key issue. In this work, a Programming Magnetic Elastic Composites (PMEC) is proposed for 3D printing to manufacture micro soft robots. The PMEC has the advantage of changing the direction of the internal magnetic field in response to changes in the external magnetic field. A Microsoft robot is designed and fabricated using PMEC inspired by an inchworm. Numerical simulations are also used to study the effect of soft robot size parameters on local stresses and optimize the structure. The results show that the microscale soft robot can crawl with a load of 2 times its weight at a speed of 6.67 mm s−1, crawl on slopes from 0° to 90°, and crawl over obstacles with a maximum height of 7 mm. In addition, active adaptation of soft robots to complex tunnel models based on external stimuli is achieved by magnetic field control. [ABSTRACT FROM AUTHOR]

Magnetic microrobots, with their small size and agile maneuverability, are well-suited for navigating the intricate and confined spaces within the human body. In vivo cargo delivery within the context of microrobotics involves the use of microrobots to transport and administer drugs and cells directly to the targeted regions within a living organism. The principal aim is to enhance the precision, efficiency, and safety of therapeutic interventions. Despite their potential, there is a shortage of comprehensive reviews on the use of magnetic microrobots for in vivo cargo delivery from both research and engineering perspectives, particularly those published after 2019. This review addresses this gap by disentangling recent advancements in magnetic microrobots for in vivo cargo delivery. It summarizes their actuation platforms, structural designs, cargo loading and release methods, tracking methods, navigation algorithms, and degradation and retrieval methods. Finally, it highlights potential research directions. This review aims to provide a comprehensive summary of the current landscape of magnetic microrobot technologies for in vivo cargo delivery. It highlights their present implementation methods, capabilities, and prospective research directions. The review also examines significant innovations and inherent challenges in biomedical applications. [ABSTRACT FROM AUTHOR]

As one of the self‐luminescence imaging approaches that require pre‐illumination instead of real‐time light excitation, afterglow luminescence imaging has attracted increasing enthusiasm to circumvent tissue autofluorescence. In this work, we developed organic afterglow luminescent nanoprobe (nanotorch), which could emit persistent luminescence more than 10 days upon single light excitation. More importantly, the nanotorch could be remote charged by 660 nm light in a non‐invasive manner, which showed great potential for real‐time tracing the location of macrophage cell‐based microrobots. [ABSTRACT FROM AUTHOR]

Oral administration is a convenient drug delivery method in our daily lives. However, it remains a challenge to achieve precise target delivery and ensure the efficacy of medications in extreme environments within the digestive system with complex environments. This paper proposes an oral multilayer magnetic hydrogel microrobot for targeted delivery and on-demand release driven by a gradient magnetic field. The inner hydrogel shells enclose designated drugs and magnetic microparticles. The outer hydrogel shells enclose the inner hydrogel shells, magnetic microparticles, and pH neutralizers. The drug release procedure is remotely implemented layer-by-layer. When the required gradient magnetic field is applied, the outer hydrogel shells are destroyed to release their inclusions. The enclosed pH neutralizers scour the surrounding environment to avoid damaging drugs by the pH environment. Subsequently, the inner hydrogel shells are destroyed to release the drugs. A set of experiments are conducted to demonstrate the wirelessly controllable target delivery and release in a Petri dish and biological tissues. The results demonstrated attractive advantages of the reported microrobot in microcargo delivery with almost no loss, remote controllable release, and drug protection by the pH neutralizers. It is a promising approach to advance next-generation precision oral therapies in the digestive system. [ABSTRACT FROM AUTHOR]

The advancements in the field of micro-robots for drug delivery systems have garnered considerable attention. In contrast to traditional drug delivery systems, which are dependent on blood circulation to reach their target, these engineered micro/nano robots possess the unique ability to navigate autonomously, thereby enabling the delivery of drugs to otherwise inaccessible regions. Precise drug delivery systems can improve the effectiveness and safety of synthetic lethality strategies, which are used for targeted therapy of solid tumors. MYCoverexpressing tumors show sensitivity to CDK1 inhibition. This study delves into the potential of Ro-3306 loaded magnetic-driven hydrogel micro-robots in the treatment of MYC-dependent osteosarcoma. Ro-3306, a specific inhibitor of CDK1, has been demonstrated to suppress tumor growth across various types of cancer. We have designed and fabricated this micro-robot, capable of delivering Ro-3306 precisely to tumor cells under the influence of a magnetic field, and evaluated its chemosensitizing effects, thereby augmenting the therapeutic efficacy and introducing a novel possibility for osteosarcoma treatment. The clinical translation of this method necessitates further investigation and validation. In summary, the Ro-3306-loaded magnetic-driven hydrogel microrobots present a novel strategy for enhancing the chemosensitivity of MYCdependent osteosarcoma, paving the way for new possibilities in future clinical applications. [ABSTRACT FROM AUTHOR]

The rising number of devices created using pop‐up microelectromechanical systems (MEMS) and related folding‐based assembly techniques highlights the need for robust design and manufacturing workflows to support the wide range of device variations. To push the bounds of miniaturization, design for manufacturing is key in dealing with fabrication challenges. Iterative building of intermediate device prototypes is a promising way to explore an often very large design space and can highlight mechanical limitations that may not be obvious to the designer. Manufacturing of pop‐up MEMS devices is, however, typically a lengthy process with lamination taking a significant percentage of the build time, compared to layer machining and component assembly. To expedite the design process, researchers often prototype multiple iterations at larger scales prior to committing to at‐scale designs. In this study, an at‐scale rapid prototyping workflow for pop‐up MEMS devices is introduced. This study also includes flexure design considerations for castellated hinges, to approach the behavior of an ideal pin joint. The new proposed workflow uses more accessible lower‐cost equipment and materials and reduces lamination time by over 95% (10 min lamination vs a 3.5 h lamination) compared to the previous heated press process, which is validated through a series of prototypes. [ABSTRACT FROM AUTHOR]

Achieving selective-individual and collective control over multiple magnetic microrobots remains a formidable challenge. Existing techniques for controlling identical magnetic swimmers are often limited to two-dimensional, small working spaces, while heterogeneous swimmers can only be controlled in small numbers without the option for collective control. In this study, we present a purely magnetic control methodology for the selective-scalable locomotion of helical magnetic swimmers within confined channels. By employing a unique gradient field distribution, referred to as the "selection field," along with space-uniform rotating fields, we establish a "selection volume" that allows swimmers within it to fully rotate, while those outside remain stationary. We explore various conditions of the selection volume to analyze the locomotion dynamics of the swimmers in relation to the position of the selection volume. Experimental results demonstrate the selective-scalable locomotion of identical robots, ranging from one to an arbitrary number (N) of robots, as well as their selective-individual manipulation for multitasking applications. Furthermore, compatibility of the proposed method with different magnetic torque-driven robots is exemplified through the selective control of rolling robots. Moreover, three-dimensional selective-scalable control is also demonstrated for four swimmers in a quasi-three-dimensional channel, as well as for two swimmers within a true three-dimensional channel. [ABSTRACT FROM AUTHOR]

It is beneficial for collective structures to simultaneously have high persistence to environmental noise and high responsivity to nontrivial external stimuli. However, without the ability to differentiate useful information from noise, there is always a tradeoff between persistence and responsivity within the collective structures. To address this, we propose adaptive time delay inspired by the adaptive behavior observed in the school of fish. This strategy is tested using particles powered by optothermal fields coupled with an optical feedback-control system. By applying the adaptive time delay with a proper threshold, we experimentally observe the responsivity of the collective structures enhanced by approximately 1.6 times without sacrificing persistence. Furthermore, we integrate adaptive time delay with long-distance transportation and obstacle-avoidance capabilities to prototype adaptive swarm microrobots. This research demonstrates the potential of adaptive time delay to address the persistence-responsivity tradeoff and lays the foundation for intelligent swarm micro/nanorobots operating in complex environments. [ABSTRACT FROM AUTHOR]

Microrobotics can address current limitations to control biofilm infections, and advance diagnostic and therapeutic modalities, in the face of increased antimicrobial resistance. Versatility in design and control of microrobots combined with targeting and detection capabilities, physical disruption and in situ drug delivery provides ample opportunities to improve the standard of care against biofilm infections. Opportunities for clinical translation and feasibility in complex physiological environments and different anatomical niches without harmful effects, mitigating the need for invasive surgical intervention. Biocompatibility and biodegradability of materials used in microrobotics is critical toward regulatory approval and clinical implementation. Potential solutions for microrobotics to overcome technical and regulatory hurdles for practical development and commercialization. The eradication of drug-resistant microbial biofilms remains an unresolved global health challenge. Small-scale robotics are providing innovative therapeutic and diagnostic approaches with high precision and efficacy. These approaches are rapidly moving from proof-of-concept studies to translational biomedical applications using ex vivo , animal, and clinical models. Here, we discuss the fundamental and translational aspects of how microrobots target the infection sites to disrupt the structural and functional traits of biofilms and their antimicrobial resistance mechanisms. We emphasize current approaches of mechanochemical disruption and on-site drug delivery that are supported by in vivo models and preclinical testing, while also highlighting diagnostics potential. We also discuss clinical translation challenges and provide perspectives for development of microrobotics approaches to combat biofilm infections and biofouling in humans. [ABSTRACT FROM AUTHOR]

Pollination is a crucial ecological process with far-reaching impacts on natural and agricultural systems. Approximately 85% of flowering plants depend on animal pollinators for successful reproduction. Over 75% of global food crops rely on pollinators, making them indispensable for sustaining human populations. Wind, water, insects, birds, bats, mammals, amphibians, and mollusks accomplish the pollination process. The design features of flowers and pollinators in angiosperms make the pollination process functionally effective and efficient. In this paper, we analyze the design aspects of the honeybee-enabled flower pollination process using the axiomatic design methodology. We tabulate functional requirements (FRs) of flower and honeybee components and map them onto nature-chosen design parameters (DPs). We apply the "independence axiom" of the axiomatic design methodology to identify couplings and to evaluate if the features of a flower and a honeybee form a good design (i.e., uncoupled design) or an underperforming design (i.e., coupled design). We also apply the axiomatic design methodology's "information axiom" to assess the pollination process's robustness and reliability. Through this exploration, we observed that the pollination process is not only a good design but also a robust design. This approach to assessing whether nature's processes are good or bad designs can be valuable for biomimicry studies. This approach can also inform design considerations for bio-inspired innovations such as microrobots. [ABSTRACT FROM AUTHOR]

Natural fibers with robust water repellency play an important role in adapting organisms to various environments, which has inspired the development of artificial superhydrophobic fibrous materials with applications in self‐cleaning, antifogging, water harvesting, heat exchanging, catalytic reactions, and microrobots. However, these highly textured surfaces (micro/nanotextured) suffer from frequent liquid penetration in high humidity and abrasion‐induced destruction of the local environment. Herein, bioinspired superhydrophobic fibrous materials are reviewed from the perspective of the dimension scale of fibers. First, the fibrous dimension characteristics of several representative natural superhydrophobic fibrous systems are summarized, along with the mechanisms involved. Then, artificial superhydrophobic fibers are summarized, along with their various applications. Nanometer‐scale fibers enable superhydrophobicity by minimizing the liquid–solid contact area. Micrometer‐scale fibers are advantageous for enhancing the mechanical stability of superhydrophobicity. Micrometer‐scale conical fibrous structures endow a Laplace force with a particular magnitude for self‐removing condensed tiny dewdrops in highly humid air and stably trapping large air pockets underwater. Furthermore, several representative surface modification strategies for constructing superhydrophobic fibers are presented. In addition, several conventional applications of superhydrophobic systems are presented. It is anticipated that the review will inspire the design and fabrication of superhydrophobic fibrous systems. [ABSTRACT FROM AUTHOR]

In this work, a closed loop control system is developed to optically localize and track micro-robots with high precision. These micro-robots (i.e., micro-conveyors) are in motion simultaneously across a smart surface.The developed method's primary objectives are to optimize their trajectories, avoid collisions between them, and control their position with micrometric resolution. This article presents and characterizes the tracking of a single micro-conveyor, and the method works similarly when multiple micro-robots move over the surface. Our tracking method starts with a scanning phase, where a 2D steering mirror, placed above the smart surface, reflects a laser beam toward the conveying surface seeking for the target. Localization occurs when this light beam reaches the micro-conveyor. By adding a retro-reflective element, that reflects the light in the same direction of the the incident light, onto the surface of the micro-conveyor, the light will be reflected towards a photodetector. Depending on the feedback from the photodetector, the steering mirror rotates to track the trajectory of the micro-conveyor. The tip-tilt angular values of the steering mirror allows the micro-conveyor position to be obtained via calibrated localization system. The aim of this work is to regulate the micro-conveyor, within a closed-loop control system, to reduce the positional error between the actual and desired position. The actual position value is measured in real-time application using our developed optical sensor. Results for tracking in the x-and y-axis have validated the proposed method, with an average tracking error less than 30 µm within a range 150 mm × 150 mm. [ABSTRACT FROM AUTHOR]

Microrobots powered by multi-physics fields are becoming a hotspot for micro–nano manufacturing. Due to the small size of microrobots, they can easily enter small spaces that are difficult for ordinary robots to reach and perform a variety of special tasks. This gives microrobots a broad application prospect in many fields. This paper describes the materials, structures, and driving principles of microrobots in detail and analyzes the advantages and limitations of their driving methods in depth. In addition, the paper discusses the detailed categorization of the action forms of microrobots and explores their diversified motion modes and their applicable scenarios. Finally, the article highlights the wide range of applications of microrobots in the fields of biomedicine and environmental protection, emphasizing their great potential for solving real-world problems and advancing scientific progress. [ABSTRACT FROM AUTHOR]

Magnetically actuated microrobots have become a research hotspot in recent years due to their tiny size, untethered control, and rapid response capability. Moreover, an increasing number of researchers are applying them for micro-/nano-manipulation in the biomedical field. This survey provides a comprehensive overview of the recent developments in magnetic microrobots, focusing on materials, propulsion mechanisms, design strategies, fabrication techniques, and diverse micro-/nano-manipulation applications. The exploration of magnetic materials, biosafety considerations, and propulsion methods serves as a foundation for the diverse designs discussed in this review. The paper delves into the design categories, encompassing helical, surface, ciliary, scaffold, and biohybrid microrobots, with each demonstrating unique capabilities. Furthermore, various fabrication techniques, including direct laser writing, glancing angle deposition, biotemplating synthesis, template-assisted electrochemical deposition, and magnetic self-assembly, are examined owing to their contributions to the realization of magnetic microrobots. The potential impact of magnetic microrobots across multidisciplinary domains is presented through various application areas, such as drug delivery, minimally invasive surgery, cell manipulation, and environmental remediation. This review highlights a comprehensive summary of the current challenges, hurdles to overcome, and future directions in magnetic microrobot research across different fields. [ABSTRACT FROM AUTHOR]

Achieving precise control over the motion position and attitude direction of magnetic microrobots remains a challenging task in the realm of microrobotics. To address this challenge, our research team has successfully implemented synchronized control of a microrobot's motion position and attitude direction through the integration of electromagnetic coils and permanent magnets. The whole drive system consists of two components. Firstly, a stepper motor propels the delta structure, altering the position of the end-mounted permanent magnet to induce microrobot movement. Secondly, a programmable DC power supply regulates the current strength in the electromagnetic coil, thereby manipulating the magnetic field direction at the end and influencing the permanent magnet's attitude, guiding the microrobot in attitude adjustments. The microrobot used for performance testing in this study was fabricated by blending E-dent400 photosensitive resin and NdFeB particles, employing a Single-Layer 4D Printing System Using Focused Light. To address the microrobot drive system's capabilities, experiments were conducted in a two-dimensional and three-dimensional track, simulating the morphology of human liver veins. The microrobot exhibited an average speed of 1.3 mm/s (movement error ± 0.5 mm). Experimental results validated the drive system's ability to achieve more precise control over the microrobot's movement position and attitude rotation. The outcomes of this study offer valuable insights for future electromagnetic drive designs and the application of microrobots in the medical field. [ABSTRACT FROM AUTHOR]